Auraninja
Eh, ragazzo!
I looked, and yes, you would be correct on that. Transferring from the GCN to the GBA to the DS and then transferring to the B/W games would seem like such a feat, but you can do that. Keep in mind, though, that in some of my list of how to get fifth gen Pokemon to learn obsolete TM egg moves, you can get a Pokemon that already knew the move to breed. For example, if you caught a Male Snorunt in XD, then it would already have Water Pulse and you can trasnsfer it to breed with any Pokemon in the "Ice Cream" family. I still counted it thought.IIRC, Slugma/Magcargo from Pokémon XD had it, just like Razor Wind Scyther.
Speaking of counting stuff, I may add Pokemon in the Ground breeding group to my list that I mentioned, even though they can learn the moves by trans-Smeargleing. I may look at that.